Carb question

[moparmarc]

Hello all,

I'm new to this forum and Mopar and have recently acquired a 1974 Charger SE (360 with a 4-barrel carb, single exhaust out the back / California model).

My question is this:

The car hesitates when I mash the throttle. If I roll on smoothly, it goes without a hitch (but it not as much fun).

I've found that I can roll on the throttle once then mash it without the sputter. For example; at idle, the motor will couch and possible stall if I just put the pedal to the floor in one shot but will rev up just fine if I do it slowly once and mash it after that. With the air cleaner lid off, mashing the throttle causes a ball of fire to shoot out of the top of the carb and the car to stall.

Any ideas? I really don't know where to even start. Too much fuel? Not enough fuel? Clogged carb? Other?

Thank you.

moparmarc

[2000 DAK 4.7]

What kind of carburator is on the car? You might want to try adjusting the accelerator pump to a higher setting. My guess is you are getting to little fuel. Check your timing while your at it.

[ehostler]

As posted in the Vintage chat area-

If it is a Holley carb, the power valve is blown and needs to be replaced.

You could also have some weak valve springs or a stuck lifter causing the valves to float. If an intake valve is closed all of the way, when combustion begins, she is going to belch up through the carb

[WS23]

moparmarc,

Both of the earlier answers you received could be correct. The question becomes WHEN do you experience this hesitation?

If it happens from a standing start, after you mash the pedal, it's called a bog. This is most often an accelarator pump issue. Usually too LITTLE gas causes a momentary lean condition and hence the bog. By adjusting for a longer duration and/or larger volume squirt, this condition is eliminated.

If it happens when you mash the pedal at cruise , it is a hessitation. This can be caused during the transition from primarys to secondary fuel metering where the powervalve (if a holley carb) is involved.

So if you have an off idle bog, adjust accelerator pump. If it gets better, but not perfect, continue to adjust for bigger squirt until fixed. If it still fails replace the powervalve.

[Rug_Trucker]

Or is it a TQ?

[moparmarc]

The carb is the stock Carter ThermoQuad. The problem does seem like more a bog (as described by WS23) as I can generally floor it once the motor has picked up some RPMs.

Could anyone point me in the right direction as to how to go about adjusting the accelerator pump? I have the workshop manual and I'd guess it's explained there but previous experience usually helps in knowing exactly what needs to be tweaked.

Thanks for all your help.

[Rug_Trucker]

You need to check for the acc. pump shot. It may need more. you can drill out the squirters. It may be time to change the seal on the pump. The symtems you are describing can be caused by the airvalves on your secondaries opening too fast. This is the problem that I have myself. The AV's look like choke plates on the back of the carb. Your TQ is probably a 800cfm. That is a lot of carb for a 360cid. It is adjustable on the driver side of the carb. There is a slotted lock nut on the end of the rod that the shaft for the AV's . In side that is a screw that controls the tension and therefore the opening rate for the carb. The TQ is really a mechanical secondary carb. The AV's artifiically make it smaller til it can handle the extracfm. I guess you can say it is a designed . I tried to adjust mine tighter and didn't road test it and kept tweeking it til I broke the spring. So my AV's are open and it really bogs!! I just went to the junkyard and bought 2 TQ's today and will replace it soon. It would be easier to adjust it with a special tool. There is a guy on this site that has a repop tool that is improved over the original Carter tool. Your screwdriver goes in through the tool to adjust the doors. There is also an adjutment on the passenger side with linkage from a diaphram on attached to the clutch linkage. I don't know exactly hoe that works(yet). You need to get the Carter carb book by Dave Emanuel. Check Amozon.com. Also there is a guy here that goes by the name DemonSizzler he reworks TQ's and is a good source. The guy that maKES THAT TOOL HAS POSTED HERE ALSO RESEARCH THE ARCHIVES for all TQ topics a few weeks back and Mr. Dr. Fiberglas is the one to get the tool from. Check the ads here I think Sizzler has an ad for his business.

[jkailholz@aol.com]

well marc, If it was my car, this is what I would do. I would run a compression test on the car to make sure the engine is in good shape. This would lead up to the next thing I would do. If everything checks out, and a recent tune-up hasn't been done. I would then look into making sure everything was up to snuff. Once you have a baseline of the shape of your engine then you can start with other things. I tend to agree that there is probably a lean condition going on in your situation. Off idle stumble is a good indication. Personally , I don't like TQ's, and I don't know your mechanical abiltity. So you will have to choose the best route for your situation. I would take that TQ off and sell it to someone who loves them. I'd either get a Holley or Edelbrock with the correct cfm that would fit your situation along with a new or used intake. Replace that restrictive single exhaust with duals. If you don't have headers they are optional. If you don't like the hassel , stick with manifolds. Put a light spring in the distributor so your advance will come in faster and make the car rev quicker. It should make your car more driveable and the seat of the pants feel should also be improved. I'd say you would pick up an easy 25HP.

[moparmarc]

Thanks to everyone for the input.

jkailholz:

What CFM is *right* for this motor? Every calculation I've seen for this requires maximum RPM and I'm really not sure what the red line is on this car. Maybe someone out there can answer this one.

Regarding the intake, do you mean replacing it with a new or used performance piece? I've seen used Edelbrock parts for sale fairly cheap. Anything I should look for?

As far as the exhaust, that's a definite yes. I've always been much happier with aftermarket on all my vehicles. The issue with headers is more $$$ than anything else.

Mechanically, I'm not afraid to tackle anything. Is there anything I can do to the TQ carb to help out until I can replace it?

Thanks again.

[jkailholz@aol.com]

I'm assuming that this engine is mostly stock , with a stock cast iron intake???? Without knowing a few more Key components, its like taking a shot in the dark. Assuming the engine is in good shape, not using oil and all the cylinders are within 10lbs. after you do a compression test, I would probably put a edelbrock performer intake or a comparable equal on. AS for the carb , I would use 650cfm edelbrock or holley. On the holley I would get a vacuum secondary model if I was going to drive the thing alot, and if I was looking for all out performance I would use a double pumper.Check your timing and Don't forget to change the springs in the distributor! This will help your engine rev more quickly and take advantage of any performance mods you have made. The springs cost only a few dollars. Make sure the car has a good Dual exhaust. Otherwise , all these parts won't work as well as there supposed to. Without knowing anymore about the car or its intended purpose, there really isn't much more I can recommend. Need more info , like rearend ratio, Convertor, cars' intended purpose, etc....

[rumblefish360]

That 650 suggestion is a good one. It will feed the engine in stock form to a nicely, mild worked up engine.

[moparmarc]

Ok, we're going to have to get into some fine details. I went and search for carbs on Edelbrock and Holley's web sites and found confusion more than anything.

The first concern is that this is a California car built after the smog exemption date. Should this be an issue? Since I'm having the car smogged this week and won't need to again for a couple of years, should I worry about what I'm putting on the car in the mean time? Assuming I keep the stock parts, would it be a big job to revert to the stock parts for smog reasons, then switch back after?

Second is, if I were to go smog-legal, Holley only lists a 600 CFM carb for my car (Model 4160 p/n 0-80454 - square bore). Would this be sufficient? Should I be looking for square bore or spread bore? What is the difference? What about with the Edelbrock intake (p/n 3776), square or spread?

Lastly, the distributor springs you're referring to. Are those the springs found on the shaft at the governor level? I checked the workshop manual and could not pinpoint exactly what I was looking for. Can you point me at an online retailer that would carry them so that I can get an idea of what to look for?

Again, thank you tremendously for your help.

[moparmarc]

BTW: The car is as if it just drove of the Dodge lot in 74. No mods, no smoke. Only a few issues with the carbs, tranny, and suspension. It will be a street car (not daily but close).

[71383bee]

moparmarc,

I may get a little flak here, but before you completely rip out your TQ and toss it into the back of the garage you may want to take the time to know the carb you have. There definately are a lot of people out there that do not like the TQ and they have some good reasons. However, there are a lot of people (like myself) that feel that the TQ is a very good performance carburator for both stock and high performance aplications. It seems to me that you are new to working on carburated cars (forgive me if I am wrong) and I feel that if you yank out the TQ and replace it with a Holley you will also run into tuning problems. Every carb out there has different ways to work on them. If you have a stock engine and a service manual then it may be worth your time to read that manual and get to know what you have. If you do take out the TQ and bolt on a holley than you better read up on how to tune a holley. Don't be afraid to tinker around with your TQ. There are plenty of TQ experts (as well as Holley and Edelbrock) to help answer your questions. The only way your going to learn about your car is to get in there and play with it. Another reason is that a brand new holley must be used with a throttle linkage adaptor and (most importantly) a square bore intake manifold. The price for all of this is pretty steep compared to a TQ rebuild kit and a couple of cans of carb cleaner. You also wont have to worry about re-installing linkage or removing the intake. Don't get me wrong this work is not that difficult, but if you have a stock engine that otherwise runs well and you have no intention of rebuilding it then I personally would not recommend bolting on a new intake and carb if all your stock carb needs is a little tune up. Sorry for the long post guys.

Good luck and have fun.

[moparmarc]

Well, the truth is my carb experience is limited to Amal carbs on old BSA motorcycles. On those, there are only five parts: the body, slides, needle, main jet and needle jet. And since there is one carb per cylinder (on my bikes, anyway), tuning is fairly simple. The whole thing can be torn apart and rebuilt in 6 minutes.

What I'm most afraid of here is to work this thing only to find that it's much better and easier to just replace it. No one, to date, had stepped up and said that Carter TQs were great once rebuilt.

What are your suggestions as far as jetting? I'm not really sure what it is running now but I'm sure the problems I'm getting are a result of incorrect fuel amounts.

[71383bee]

Moparmarc,

By no means am I an expert on TQ's, but I have heard and seen a lot of good cars equiped with them. Several of the editors from Mopar Muscle just rave about them and I know there are several people on this chat that do like them. In fact, the guys at Mopar Muscle wrote a real detailed article about rebuilding TQ's and showed some easy performance mods that anyone can do. They even built a real nice 400 that put out 420hp and 440tq with a rebuilt TQ.

From what i heard you should pay special attention to rug trucker's comments. It could be that you just need to adjust the secondary air valve spring. You really should pick up that tool however. Year one even sells them for $14. As far as rejetting I would not worry about it if I were you. The only jets in a TQ are for the primarys. The secondaries are basically operated off of the vacum created by the engine as you open the throttle up. The secondaries open mechanically and the air valve will open more slowly depending on the spring tension and choke position. When they open up it actually pulls the gas out of the carburator. (Guys, correct me if I am wrong!) This is why some people will say that you can not over carburate with a TQ because the amount of gas you pull relates directly to how efficient your engine is.

I'm not trying to tell you that Holley's and Edelbrock's are no good. It just seems that for your aplication you may be better off just buying a rebuild kit and doing a good rebuild on the TQ. I bet you probably will be pretty impressed with the results. Besides this way you wont need a squarebore adaptor or a new square bore manifold and your linkage stays the same.

If you do get rid of the TQ then I would be more than happy to take it off your hands =)

[rumblefish360]

The carter T-Q is an easy to work on and understand carb. IT IS SIMPLE! Do not be afraid! Theres a book out on them. Its everything from history to rebuilding them. Its by Dave Emanuel ans S-A Design books.
There a cake walk. Go for it!
Almost forgot...the secondarys have jets in the floor. You can richen up or lean out the mixture by bending the secondary air door. The engine will pull what it needs. If you change the hets, thats where it can get tricky. However, the only jets that I've seen for sale were worth more than Gold.
If ANYBODY nows where to get them for a real price, E-mail me.

[jkailholz@aol.com]

Marc , I have a Jegs catalog with the springs in it and the part # is 312-p2932675 and they cost $6.99. You replace your stock springs in your distributor with these and they will bring the advance in sooner.The springs are underneath the plate in the distributor. Pull your cap and rotate the engine and you should be able to see them. You can also with the distributor cap off turn the rotor. That will let you feel the factory tension of the stock springs. Then compare with the HP springs you put in. You will notice that the HP springs are much lighter. Phone number is 1-800-345-4545. The carb you mentioned earlier that would be "legal" for your car would work, but it won't be the best for performance. The emission legal carbs are set up way too lean from the manufacturer to run right. You would probably have to rejet or put in different metering rods to make it run good. I don't know what you can get away with as far as your emissions testing goes, but If you have a bunch of smog equipment on your car, After you pass the test , I would rip it all off and save it . Then put the "good" parts on untill you need to go for another "check up". How about putting some historical plates on the car?? Would that make you emissions exempt? As for the TQ , If you really want to learn how to work on one, I guess you couldn't go wrong. but if you screw it up somehow, You can always buy a new carb. The reason I don't like TQ's is because you cant just flip open a catalog and order up what ever you want for one. If you need to "tune" one, you have to drill this , measure that, and it seems any time you drill something, You can't go back to the way it was.

[Rug_Trucker]

Dont screw with the TQ with out the book. Get ahold of Demon Sizzler. If it isn't a daily driver send the carb to him and he will rework it. Or order one from him already prepped.

[carguy]

Hello Marc: I agree with jkailholtz, you need to check everything (timing, vacuum, plugs, points, Distributor advance, etc...). A hesitation can be caused by many things. If you start swapping carbs, intakes, or what
ever. This could get expessive. Been there, done that. I have a stock 67 273 which I put a Edl 600 and a 72 340 intake on (orgially a 2 bbl). The car (67 Belvedere) runs great. You should be able to bolt on a 750 Edl without a problem. You may have to play with the jets and metering rods abit. But should run correctly right out of the box. And you can get a throddle adaptor from edelbrock to make it work correctly. Good lock...